reference instfs_uuid from instfs direct upload

refs RECNVS-521

* previously instfs file upload returned only the
instfs uuid as `uuid`
* instfs file upload now returns canvas capture
data, which includes the canvas uuid
* instfs uuid has been renamed to `instfs_uuid`

test plan:
* specs

Change-Id: I1f77f3dd1952fbd275ae67c399ff04ef6533785b
Reviewed-on: https://gerrit.instructure.com/157118
Reviewed-by: Michael Jasper <mjasper@instructure.com>
Tested-by: Jenkins
Product-Review: Xander Moffatt <xmoffatt@instructure.com>
QA-Review: Xander Moffatt <xmoffatt@instructure.com>

lib/inst_fs.rb

@@ -127,9 +127,9 @@ module InstFS
       response = CanvasHttp.post(url, form_data: data, multipart:true)
       if response.class == Net::HTTPCreated
         json_response = JSON.parse(response.body)
-        return json_response["uuid"] if json_response.key?("uuid")
+        return json_response["instfs_uuid"] if json_response.key?("instfs_uuid")
 
-        raise InstFS::DirectUploadError, "upload succeeded, but response did not containe a \"uuid\" key"
+        raise InstFS::DirectUploadError, "upload succeeded, but response did not containe an \"instfs_uuid\" key"
       end
       raise InstFS::DirectUploadError, "received code \"#{response.code}\" from service"
     end

spec/lib/inst_fs_spec.rb

@@ -393,18 +393,18 @@ describe InstFS do
 
     context "direct upload" do
       it "makes a network request to the inst-fs endpoint" do
-        uuid = "1234-abcd"
+        instfs_uuid = "1234-abcd"
         allow(CanvasHttp).to receive(:post).and_return(double(
           class: Net::HTTPCreated,
           code: 200,
-          body: {uuid: uuid}.to_json
+          body: {instfs_uuid: instfs_uuid}.to_json
         ))
 
         res = InstFS.direct_upload(
           file_name: "a.png",
           file_object: File.open("public/images/a.png")
         )
-        expect(res).to eq(uuid)
+        expect(res).to eq(instfs_uuid)
       end
     end
   end